JP6288525B2 - Solid-state imaging device, imaging device, electronic device, and manufacturing method - Google Patents

Description

  The present disclosure relates to a solid-state imaging device, an imaging device, an electronic device, and a manufacturing method, and more particularly, to a solid-state imaging device, an imaging device, an electronic device, and a manufacturing method that can suppress a decrease in light receiving sensitivity and color mixing.

  2. Description of the Related Art Conventionally, a solid-state imaging device represented by a CMOS image sensor is mounted on an imaging apparatus such as a digital still camera or a digital video camera.

  FIG. 1 shows a cross-sectional view of a conventional general solid-state imaging device.

  The solid-state imaging device 10 is configured by laminating an on-chip lens 11, a color filter 12, a light shielding unit 13, a sensor unit 14, and the like in order from the light incident side. Further, when the on-chip lens 11 is formed of an inorganic film having a high refractive index such as SiN, a planarizing layer 15 for eliminating the step of the color filter 12 is provided between the on-chip lens 11 and the color filter 12. Provided.

  In the solid-state imaging device 10, incident light is condensed on the lower layer side by the on-chip lens 11, is incident on the sensor unit 14 through the color filter 12, and photoelectric conversion is performed in the sensor unit 14.

  By the way, in the general solid-state image sensor 10, the on-chip lens 11 corresponding to each pixel is integrally formed in the lateral direction by the same material. As a result, as shown in the figure, out of light incident on a region corresponding to a certain pixel of the on-chip lens 11, it leaks to an adjacent pixel and does not reach the sensor unit 14 that should be incident. In addition, there may be a light incident on the sensor unit 14 of the adjacent pixel. Such a phenomenon leads to a decrease in light receiving sensitivity and a deterioration in color mixing, so some countermeasure is required.

  Therefore, as a countermeasure against the above phenomenon, the present applicant has proposed a solid-state imaging device in which a groove is provided at a boundary between regions corresponding to each pixel of the on-chip lens 11 formed integrally (for example, Patent Documents). 1).

  FIG. 2 is a cross-sectional view of a solid-state imaging device to which the above countermeasure is applied.

  In the solid-state imaging device 20, the light is totally reflected by the groove 21 at the boundary of the region corresponding to each pixel of the on-chip lens 11. Therefore, it is possible to prevent color mixing by preventing the incident light from leaking from the sensor unit 14 of the pixel that should be incident to the sensor unit 14 of the adjacent pixel.

JP2008-270679

  Incidentally, as shown in FIG. 2, a photolithography technique is usually used for the step of providing the groove 21 in the on-chip lens 11. When the photolithography technique is used, a deviation is easily generated in the overlapping of the positions of the grooves 21.

  Further, the width of the groove 21 is several hundred nm, the width of the groove 21 occupying the on-chip lens 11 is relatively wide, and the area of the on-chip lens 11 is narrowed, so that the light collection efficiency is deteriorated. It will be.

  For example, as shown in FIG. 3, in the solid-state imaging device 30 in which another material film 31 made of a material different from the on-chip lens 11 is formed on the on-chip lens 11 provided with the groove 21, The other material will enter. In this case, since the difference in refractive index between the on-chip lens 11 and the other material that has entered the groove 21 is reduced, the effect of preventing the leakage of incident light by providing the groove 21 is diminished.

  Further, when the flattening layer 15 is provided as shown in FIGS. 1 to 3, the distance from the on-chip lens 11 to the sensor unit 14 is increased by the flattening layer 15, so that sensitivity deterioration and defect Deterioration and deterioration of oblique incidence characteristics can also be a problem.

  The present disclosure has been made in view of such a situation, and is intended to suppress deterioration in sensitivity of a solid-state imaging device.

The solid-state imaging device according to the first aspect of the present disclosure includes a sensor unit that generates an electrical signal in response to incident light, a color filter that covers the sensor unit, and the incident light that enters the sensor unit via the color filter. A lens formed of a laminated film made of a predetermined lens material, and the lens is formed on an upper layer of the color filter without providing a flattening layer for eliminating a step of the color filter. The lens has a slit, and the upper side of the slit is closed .

  A refractive index adjusting film may be provided between the color filter and the lens.

  The refractive index adjusting film can be made of SiON.

  The slit may be formed at a boundary of a corresponding region of each pixel of the lens.

  The upper side of the slit can be closed by the same predetermined lens material as the lens or SiON different from the lens material.

  The predetermined lens material may be SiN.

  The solid-state imaging device may be a front side illumination type or a back side illumination type image sensor.

  The solid-state imaging device according to the first aspect of the present disclosure may further include a film made of a material having a refractive index smaller than that of the predetermined lens material on the lens.

  The solid-state imaging device may have a CSP structure.

  The width of the slit may be less than 100 nm.

An imaging apparatus according to a second aspect of the present disclosure is an imaging apparatus on which a solid-state imaging element is mounted, and the solid-state imaging element includes a sensor unit that generates an electrical signal according to incident light, and the sensor unit. A color filter that covers the lens, and a lens formed of a laminated film of a predetermined lens material for condensing the incident light on the sensor unit via the color filter, and the lens has a step of the color filter. It is formed in the upper layer of the color filter without providing a flattening layer for eliminating, and the lens has a slit, and the upper side of the slit is closed .

An electronic device according to a third aspect of the present disclosure is an electronic device having an imaging unit, and the solid-state imaging device mounted on the imaging unit includes a sensor unit that generates an electrical signal according to incident light; A color filter covering the sensor unit; and a lens formed of a laminated film of a predetermined lens material for condensing the incident light on the sensor unit via the color filter, the lens being the color filter Is formed in the upper layer of the color filter without providing a flattening layer for eliminating the step, and the lens has a slit, and the upper side of the slit is closed .

  In the first to third aspects of the present disclosure, incident light collected by the lens is incident on the sensor unit via the color filter without passing through the planarization layer.

  The manufacturing method according to the fourth aspect of the present disclosure includes a sensor unit that generates an electrical signal in response to incident light, and a laminated film made of a predetermined lens material for condensing the incident light on the sensor unit. In the method of manufacturing a solid-state imaging device in which a slit is formed in the lens and the upper side of the slit is closed, the lens material layer is formed into a hemisphere for each pixel. The hemispherical lens material is further laminated with the same lens material to increase the size of the hemispherical lens material, and the hemispherical shape corresponding to each pixel whose size is increased. The slit region is formed by etching the bonding region of the lens material, and film formation is performed on the lens material in which the slit is formed.

  In the fourth aspect of the present disclosure, a lens material layer is formed in a hemispherical shape for each pixel, and the same lens material is further laminated on the hemispherical lens material, thereby forming the hemispherical shape. The size of the lens material is increased, and the joining area of the hemispherical lens material corresponding to each pixel with the increased size is etched to form a slit, and the slit material is formed on the lens material. Film formation is performed.

  According to the first to third aspects of the present disclosure, it is possible to suppress sensitivity deterioration.

  According to the fourth aspect of the present disclosure, it is possible to manufacture a solid-state imaging device capable of suppressing sensitivity deterioration.

It is sectional drawing of the conventional general solid-state image sensor. It is sectional drawing of the solid-state image sensor which provided the groove | channel in the conventional on-chip lens. It is sectional drawing of the solid-state image sensor which formed the other material film | membrane on the on-chip lens. It is sectional drawing of the solid-state image sensor which is 1st Embodiment of this indication. It is a top view of the solid-state image sensor which is a 1st embodiment of this indication. It is a figure showing the total reflection angle by a slit. It is a figure showing the relationship between the length of a slit, and light reception sensitivity. It is a flowchart explaining the formation process of a slit. It is a figure for demonstrating the process of the formation process of a slit. It is sectional drawing of the solid-state image sensor which is 2nd Embodiment of this indication. It is sectional drawing of the solid-state image sensor which is 3rd Embodiment of this indication. It is sectional drawing of the solid-state image sensor which is 4th Embodiment of this indication.

  Hereinafter, the best mode for carrying out the present disclosure (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.

[Configuration example of the solid-state imaging device 50 according to the first embodiment of the present disclosure]
FIG. 4 shows a cross-sectional view of the solid-state imaging device 50 according to the first embodiment of the present disclosure. Among the constituent elements of the solid-state imaging device 50, the constituent elements common to the solid-state imaging device 10 of FIG.

  The solid-state imaging device 50 is configured by laminating an on-chip lens 11, a planarization layer 15, a color filter 12, a light shielding unit 13, and a sensor unit 14 in order from the light incident side. A slit 51 is opened at the boundary of the region corresponding to each pixel inside the.

  Although not shown, a film made of a resin material having a refractive index smaller than that of the on-chip lens 11 may be formed on the on-chip lens 11 provided with the slits 51.

  FIG. 5 is a top view of the solid-state image sensor 50. As shown in the figure, the slit 51 is provided at a boundary between regions corresponding to pixels adjacent to the on-chip lens 11 in the vertical and horizontal directions. In other words, the area corresponding to each pixel of the on-chip lens 11 is surrounded by the slit 51.

  However, the cross-sectional view shown in FIG. 4 is a cross section taken along the line segment AA ′ shown in FIG. 5, and the slit 51 does not exist in the cross section (not shown) of the line segment BB ′ shown in FIG. 5.

  In the solid-state imaging device 50, incident light is condensed on the lower layer side by the on-chip lens 11, is incident on the sensor unit 14 through the color filter 12, and photoelectric conversion is performed in the sensor unit 14.

  The difference between the slit 51 of the solid-state image sensor 50 and the groove 21 of the fixed image sensor 20 shown in FIG. 2 is that the slit 51 is sufficiently narrower than the groove 21. Specifically, the width of the groove 21 formed by photolithography is several hundred nm, whereas the width of the slit 51 formed by plasma etching (EB) is several nm. The width of the slit 51 is preferably less than 100 nm.

  Further, the upper portion of the groove 21 is open, whereas the upper portion of the slit 51 is blocked by the same material as the on-chip lens 11. The formation of the slit 51 will be described later with reference to FIGS.

FIG. 6 shows the total reflection angle by the slit 51. When the refractive indexes of the on-chip lens 11 and the slit 51 (ie, air) are n ₁ and n ₂ and the total reflection angle is θ ₁ , the following relationship is known.
sinθ ₁ > n ₂ / n ₁
For example, when a conventional general material is used for the on-chip lens 11, the total reflection angle θ ₁ is 43 degrees, and when SiN is used for the on-chip lens 11, the total reflection angle θ ₁ is 30 degrees. Become.

  FIG. 7 shows the result of verifying the relationship between the length (depth) of the slit 51 and the light receiving sensitivity. As can be seen from the figure, the longer the slit 51 is, the better the light receiving sensitivity is.

[Production method]
Next, the formation process of the slit 51 of the solid-state imaging device 50 according to the embodiment of the present disclosure will be described with reference to FIGS. 8 and 9.

  FIG. 8 is a flowchart for explaining the formation process of the slits 51 of the solid-state imaging device 50. FIG. 9 is a cross-sectional view of the solid-state imaging device 50 for explaining the process of forming the slits 51. However, in FIG. 9, illustration of the lower layer side than the color filter 12 of the solid-state imaging device 50 is omitted.

  In step S1, as shown in FIG. 9A, a planarizing layer 15 is provided above the color filter 12, and a high refractive index lens material (on the on-chip lens 11) is formed on the planarizing layer 15. For example, a SiN) layer is formed. Further, a hemispherical lens shape is formed on the lens material layer by photolithography.

  In step S2, as shown in FIG. 9B, the lens shape formed in step S1 is transferred to the lens material by dry etching.

  In step S3, as shown in FIG. 9C, a layer of the same lens material is further laminated on the lens-shaped lens material. In the process of laminating this film, the hemisphere of the lens material gradually increases, and a lens material bonding region having a fragile film quality is accurately formed at the position where the hemispheres are bonded to each other (that is, the position where the slit 51 is provided). The

  In FIG. 9C, a line is drawn to show the boundary between the hemispherical portion transferred to the lens material in step S2 and the portion laminated in step S3. Since it is formed of the above material, there is no optical boundary. The same applies to D in FIG. 9 and E in FIG.

  In step S4, as shown in FIG. 9D, the slit 51 is opened in the lens material joining region where the hemispheres are joined together by etching. In addition, since the lens material joining region is fragile, the slit 51 can be quickly and easily opened by etching. In addition, since the lens material bonding region exists exactly at the boundary between the hemispheres and the lens material bonding region is etched, the slit 51 can be formed by self-alignment.

  In step S5, as shown in FIG. 9E, film formation with the same lens material is performed on the slit 51, and the upper portion of the slit 51 is closed. Further, the upper layer of the on-chip lens 11 having the slit 51 whose upper side is closed is formed with a material different from the same lens material (for example, SiON), or a resin film is formed thereon. It may be. Above, description of the formation process of the slit 51 is complete | finished.

  As described above, in the solid-state imaging device 50 provided with the slits 51, the light that has leaked to the adjacent pixels inside the on-chip lens 11 in the solid-state imaging device 10 shown in FIG. It can be reflected and incident on the sensor portion 14 of the original pixel. Therefore, it is possible to increase the light receiving sensitivity and suppress color mixing.

  Further, since the upper side of the slit 51 is blocked, it is possible to prevent the area of the on-chip lens 11 from being narrowed as in the solid-state imaging device 20 shown in FIG. .

  Further, another material having a refractive index smaller than that of the lens material may be formed on the on-chip lens 11 as in the solid-state imaging device 30 of FIG. Even in this case, since the other material does not enter the slit 51 due to the upper side of the slit 51 being blocked, the reduction of the total reflection effect by the slit 51 can be prevented.

[Configuration Example of Solid-State Image Sensor 60 According to the Second Embodiment of the Present Disclosure]
FIG. 10 shows a cross-sectional view of a solid-state imaging device 60 according to the second embodiment of the present disclosure. The solid-state imaging device 60 is obtained by omitting the planarization layer 15 from the solid-state imaging device 50 of FIG.

  That is, in the solid-state imaging device 60, the on-chip lens 11 is formed directly on the color filter 12. For the solid-state imaging device 60, a film made of a resin material having a refractive index smaller than that of the on-chip lens 11 may be formed on the on-chip lens 11 provided with the slits 51.

  Compared with the solid-state image sensor 50, since the distance between the on-chip lens 11 and the sensor unit 14 is shorter than the solid-state image sensor 50, the solid-state image sensor 60 has sensitivity degradation, defect degradation, and oblique incidence characteristics. Deterioration can be suppressed.

  Note that the manufacturing method of the solid-state imaging device 60 is the same as the manufacturing method of the solid-state imaging device 50 described above, and thus the description thereof is omitted.

[Configuration Example of Solid-State Imaging Device 70 According to Third Embodiment of the Present Disclosure]
FIG. 11 shows a cross-sectional view of a solid-state imaging device 70 according to the third embodiment of the present disclosure. The solid-state imaging device 70 is obtained by omitting the planarization layer 15 from the solid-state imaging device 10 of FIG.

  That is, in the solid-state imaging device 70, the on-chip lens 11 is formed directly on the color filter 12. Note that a film made of a resin material or the like having a refractive index smaller than that of the on-chip lens 11 may be formed on the solid-state imaging element 70 as well.

  Since the solid-state imaging device 70 is not provided with the slit 51 in the on-chip lens 11 as in the first and second embodiments described above, the effect of increasing the light receiving sensitivity and suppressing color mixing is obtained. I can't. However, since the distance between the on-chip lens 11 and the sensor unit 14 is shorter than the solid-state imaging device 10 shown in FIG. Deterioration of characteristics can be suppressed.

  The method for manufacturing the solid-state image sensor 70 is the same as the method for manufacturing the solid-state image sensor 50 described above except that the step of providing the slits 51 is omitted, and a description thereof will be omitted.

[Configuration example of solid-state imaging device 80 according to the fourth embodiment of the present disclosure]
FIG. 12 shows a cross-sectional view of a solid-state imaging device 80 according to the fourth embodiment of the present disclosure. The solid-state imaging device 80 is obtained by omitting the planarization layer 15 from the solid-state imaging device 10 of FIG. 1, and the refractive index of the on-chip lens 11 and the refractive index of the color filter 12 are formed on the color filter 12. A refractive index adjusting film 81 such as SiON having an intermediate refractive index is provided.

  That is, in the solid-state imaging device 80, the refractive index adjustment film 81 is formed on the color filter 12, and the on-chip lens 11 is formed thereon. Note that a thin film such as a resin material having a refractive index smaller than that of the on-chip lens 11 may be formed on the solid-state imaging element 80.

  Since the solid-state imaging device 80 is not provided with the slit 51 in the on-chip lens 11 as in the first and second embodiments described above, the effect of increasing the light receiving sensitivity and suppressing color mixing is obtained. I can't. However, since the distance between the on-chip lens 11 and the sensor unit 14 is shorter than the solid-state imaging device 10 shown in FIG. Deterioration of characteristics can be suppressed. Moreover, since the interface reflection can be suppressed by providing the refractive index adjusting film 81, an improvement in sensitivity can be expected. Note that the refractive index adjustment film 81 can also be provided in the first and second embodiments.

  As for the manufacturing method of the solid-state imaging device 70, the solid-state imaging device 50 described above is provided except that a step of providing the refractive index adjusting film 81 on the color filter 12 and a step of providing the slit 51 are omitted. Since this is the same as the manufacturing method, the description thereof is omitted.

  Note that the solid-state imaging devices 50, 60, 70, and 80 according to the first to fourth embodiments of the present invention can be applied to any of the front side illumination type and back side illumination type image sensors. It is also suitable for a CSP (chip size package) structure.

  Furthermore, the solid-state imaging devices 50, 60, 70, and 80 according to the first to fourth embodiments of the present invention are applied to an arbitrary electronic device including an imaging unit in addition to an imaging device such as a digital video camera or a digital still camera. it can.

  The embodiment of the present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present disclosure.

In addition, this technique can also take the following structures.
(1)
A sensor unit that generates an electrical signal in response to incident light;
A color filter covering the sensor unit;
A lens formed of a laminated film of a predetermined lens material for condensing the incident light on the sensor unit through the color filter, and
The lens is formed on an upper layer of the color filter without providing a flattening layer for eliminating a step of the color filter.
(2)
The solid-state imaging device according to (1), wherein a slit is formed in the lens, and an upper side of the slit is closed.
(3)
A refractive index adjustment film is provided between the color filter and the lens. The solid-state imaging device according to (1) or (2).
(4)
The solid-state imaging device according to (2), wherein the refractive index adjustment film is SiON.
(5)
The solid-state imaging device according to any one of (1) to (4), wherein the slit is formed at a boundary of a region corresponding to each pixel of the lens.
(6)
The solid-state imaging device according to any one of (1) to (5), wherein an upper side of the slit is covered with the same predetermined lens material as that of the lens or SiON different from the lens material.
(7)
The solid-state imaging device according to (6), wherein the predetermined lens material is SiN.
(8)
The solid-state image pickup device according to any one of (1) to (7), wherein the solid-state image pickup device is a front-illuminated or back-illuminated image sensor.
(9)
The solid-state imaging device according to any one of (1) to (8), further including a film made of a material having a refractive index smaller than that of the predetermined lens material on an upper layer of the lens.
(10)
The solid-state imaging device according to any one of (1) to (9), wherein the solid-state imaging device has a CSP structure.
(11)
The width of the slit is less than 100 nm. The solid-state imaging device according to any one of (2) to (10).

  DESCRIPTION OF SYMBOLS 11 On-chip lens, 12 Color filter, 13 Light-shielding part, 14 Sensor part, 15 Planarization layer, 50 Solid-state image sensor, 51 Slit, 60, 70, 80 Solid-state image sensor, 81 Refractive index adjustment film

Claims (13)

A sensor unit that generates an electrical signal in response to incident light;
A color filter covering the sensor unit;
A lens formed of a laminated film of a predetermined lens material for condensing the incident light on the sensor unit through the color filter, and
The lens is formed in the upper layer of the color filter without providing a flattening layer for eliminating the step of the color filter ,
A solid-state imaging device in which a slit is formed in the lens and an upper side of the slit is closed . A refractive index adjusting film is provided between the color filter and the lens.
The solid-state imaging device according to claim 1 . The refractive index adjusting film is SiON.
The solid-state imaging device according to claim 2 . The slit is formed at the boundary of the corresponding region of each pixel of the lens.
The solid-state imaging device according to claim 1 . The upper side of the slit is closed with the same predetermined lens material as the lens or a SiON different from the lens material.
The solid-state imaging device according to claim 1 . The predetermined lens material is SiN.
The solid-state imaging device according to claim 2 . The solid-state imaging device is a front-illuminated or back-illuminated image sensor.
The solid-state imaging device according to claim 1 . A film made of a material having a refractive index smaller than that of the predetermined lens material is further provided on the upper layer of the lens.
The solid-state imaging device according to claim 1 . The solid-state imaging device has a CSP structure.
The solid-state imaging device according to claim 1 . The width of the slit is less than 100 nm
The solid-state imaging device according to claim 1 . An imaging device equipped with a solid-state imaging device,
The solid-state imaging device is
A sensor unit that generates an electrical signal in response to incident light;
A color filter covering the sensor unit;
A lens formed of a laminated film of a predetermined lens material for condensing the incident light on the sensor unit through the color filter, and
The lens is formed in the upper layer of the color filter without providing a flattening layer for eliminating the step of the color filter ,
An imaging apparatus in which a slit is formed in the lens, and an upper side of the slit is closed . An electronic device having an imaging unit,
The solid-state imaging device mounted on the imaging unit is
A sensor unit that generates an electrical signal in response to incident light;
A color filter covering the sensor unit;
A lens formed of a laminated film of a predetermined lens material for condensing the incident light on the sensor unit through the color filter, and
The lens is formed in the upper layer of the color filter without providing a flattening layer for eliminating the step of the color filter ,
An electronic device in which a slit is formed in the lens, and an upper side of the slit is closed . A sensor unit that generates an electrical signal in response to incident light;
A lens formed of a laminated film of a predetermined lens material for condensing the incident light on the sensor unit;
In the method for manufacturing a solid-state imaging device, the lens has a slit, and the upper side of the slit is closed.
The lens material layer is shaped into a hemisphere for each pixel,
Increasing the size of the hemispherical lens material by further laminating the same lens material on the hemispherical lens material,
Etching the hemispherical lens material joint area corresponding to each pixel whose size has been increased to open the slit,
A manufacturing method in which film formation is performed on the lens material in which the slit is formed.

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